\\[-1.8ex] Soil Heterogeneity & $-$0.561$^{***}$ & $-$0.401$^{**}$ & $-$0.394$^{***}$ & $-$0.436$^{***}$ & $-$0.446$^{***}$ & $-$0.445$^{***}$ \\ 
  & (0.167) & (0.170) & (0.147) & (0.129) & (0.129) & (0.129) \\ 
\\[-1.8ex] 
Observations & 23,307 & 23,027 & 22,839 & 17,210 & 19,715 & 19,561 \\ 
R$^{2}$ & 0.365 & 0.350 & 0.369 & 0.417 & 0.485 & 0.482 \\ 
